Automatic nailer



Sept. 24, 1963 H, M, GREY., JR, ETAL 3,104,395

AUTOMATIC AILER Filed Nov. 22, z1957 i Y 4 Sheets-Sheet `l 37 a@ 33 AR zo :-gJ/l/w/ las Eid f2 I no Wl '32 weer F 9715 mig-tm H. M. GREY, JR., ETAL Sept. 24, 1963 AUTOMATIC NAILER Filed Nov. 22.1951

4 Sheets-Sheet '2 INVENTORS ATTORNEYS Sept. 24, 1963 H, M. GREY, JR., ETAI. 3,104,395

AUTOMATIC NAILER Filed Nov. 22, 1957 4 Sheets-Sheet 5 INVENTORSZ HucvH M.GP EY,JR. and HENRY E. COLEJ l? 7.11 MMMWQ ATTORNEYS 4 Sheets-Sheet 4 -HuGH M COLEY ATTORNEYS Sept. 24, 1963 H. M. GREY, JR., ETAL AUTOMATIC NAILER Filed Nov, 22, 1957 United States Patent O 3,104,395 AUTOMATIC NAHER Hugh M. Grey, Jr., 61 Grove St., and Henry E. Coley, Rte. 2, Box 830, both of Concord, N.C. Filed Nov. 22, 1957, Ser. No. 698,086 21 Claims. (Cl. 1 6) This invention relates to improvements in a pneumatically operated automatic nailing machine.

Automatic nailers which are known in the prior art are subject to numerous operating difficulties. Among these is the problem of obtaining instantaneous percussive force from the nail driving means to insure that the nail is completely driven into place. Prior art nailers have experienced ydificulty in retaining the nail driving means in a retracted position until a predetermined amount of pressure is placed upon the nail driving means to exert suiiicient force thereon for completely driving the nail in place with a single power stroke of the nail driving means. Since the parts of a nailing machine must absorb large percussive forces, prior art nailing machines have also found it troublesome to minimize metal fatigue in -these parts, thus creating the necessity for constant repair and replacement of parts which fail.

Another problem which has presented itself in prior art nailing machines is the proper feeding `of nails to the machine. Attempts have been made to overcome this difficulty by installing tiltable hoppers connected to a nail feeding track and to the nail driving means whereby the hopper is agitated as a result of the movement of the nail driving means downwardly to position a plurality of nails `on the track from where they can be released to the nailer for being driven in place by the nail driving means. Such assemblies require a number of moving parts which are subjected to rapid wear with the inevitable result that numerous repairs are required to keep the nailing machine in operable condition.

It is common to provide a receptacle below the nail 'driving means Ito accommodate an individual nail prior to its being `driven in place by the nail driving means. The prior art has concerned itself with efforts to insure that the nail is .properly alined within the receptacle to receive the full force of Ilthe nail driving means on lits head. AOne approach has been gravity feeding of the nails to the receptacle, but this has not proved to be consistently reliable in the past because of the rapid acceleration `of the nails as they travel down a track to the receptacle. When the lead nail enters the receptacle traveling at such a high rate of speed, it frequently strikes a side |wall of the receptacle with great force causing it to bounce away from its intended position in the receptac-le and to assume a cocked position. When in this cocked position, the nail is incapableof being driven in place by the nail driving means.

Many of the prior art nailers are constructed to be used only with a specially designed nail and cannot be operated unless a supply of these special nails is available. The cost of these specially designed nails is prohibitive when compared to that of nails in common use which are readily vavailable almost everywhere.

Another problem has been experienced in this field when attempts have been made to drive a nail into a hard surface, such as a steel band surrounding hardwood Y encountered in the manufact-ure of barrels, without bending the nail as it is driven by the automatic nailer. This problem is commonly approached by strongly supporting the -tip of the nail in the nail holding receptacle of the nailer. While this approach eifectively prevents the bending of the nail, it necessitates a slower driving action on the part of the nailer, as the nail driving plunger literally pushes the nail in place.

kPatented Sept. 24, 1963 For the most part, the automatic nailers in the prior art are unwieldly, cumbersome, and slow in operation.

It is theprincipal object of this invention to correct these and other defects present in the prior art pneumatically operated nailers.

A more specic object of this invention is to provide a pneumatically operated nailer in which a single means is effective to bring about the power stroke of the nail driving means and the feeding of a singlenail into position to be `driven as successive steps in a cycle of operation.

Another basic object of this invention is to provide an automatic nailer in which compressed air effects the power stroke of the nail driving means and the exhaust from by said latching means instantaneously releases the nail driver for its power stroke.

Another object of this invention is to provide a latching mechanism lfor a .pneumatically operated nailer in which ball elements are resiliently pressed intovgripping engagement with a control pin on the nail driver, the latching mechanism being biased upwardly by resilient means, whereupon a predetermined amount* of pressure between the nail driver and the latchin-g mechanism is effective to overcome the upward Vbiasing 'force to the resilient means thereby permitting a cam washer to urge the ball elements outwardly away from gripping engagement with the control pin of the nail driver to instantaneously release the same.

Another object of this invention is to provide a latching mechanism for a pneumatically operated nailer in which the housing confining the nailer mechanism has an annular outwardly tapered camsurface positionedtherein; the latching mechanism comprises segmental pivoting means mounted within the annular cam surface and having a complementary surface for engagement therewith Vthe nail driving means.

Another object of this invention is to provide a pneumatically operated nailer in which there are krelatively few moving parts to minimize Wear and in which allowances have been made for the large percussive forces developed by the nailer -to minimize metall fatigue in the parts of the nailer. j

Another object of'this invention is to provide a slowdown attachment on the track down which the nails are fedto the receptacle below the nail driving means to insure that the nails enter the receptacle and laline themselves properly therein. I

Another object ofthis invention is to provide a pneumatically operated nailer which can be used with a comnailer is capable of driving the` nail into a hard surface La without bending it, although the tip of the nail is not supported, because of the tremendous percussive force of the nail driving means upon the nail. The nailer vforming this invention is therefore faster in operation drawings, in which- FIGURE 1 is a side elevational view with parts broken away of an automatic nailer 4according to the present invention;

FIGURE 2 is a top plan view with parts broken away of the automatic nailer shown in FIGURE l;

FIGURE 3 is a fragmentary elevational View, partially in section, of the valve arrangement for actuating the automatic nailer, the valve being shown in the position it assumes subsequent to the driving of a nail;

FIGURE 4 is a fragmentary elevational View, partially in section, showing the actuating valve for the automatic nailer in the position it assumes when compressed air is being delivered to the vnailer housing prior to the driving of a nail;

lFIGURE 5 is a transverse sectional view of the track `and gate mechanism positioned thereon for delivering nails to the automatic nailer taken along line 5-5 in FIGURE 1;

FIGURE 6 is a fragmentary bottom plan view of the Atrack for feeding nails to the automatic nailer looking along the line 6 6 in FIGURE 1;

FIGURE 7 is a side elevational view of the automatic nailer housing looking in the direction of arrow 7 in FIGURE 1;

FIGURE 8 is a longitudinal sectional view taken along line 8-8 in iFIGURE 7;

FIGURE 9 is an enlarged fragmentary longitudinal vsectional view similar to FIGURE 8 but showing the latching mechanism parts in the positions they assume just prior to the release of the piston;

FIGURE 10 is a transverse sectional view, partially in plan, taken along line 10-10 in FIGURE 9;v

FIGURE 11 is a fragmentary transverse sectional view .taken along line 11-11 in FIGURE 8 and showi-ng the nail feeding track and the receptacle for holding a nail in position to be driven;

`LFIGURE 12 -is a longitudinal sectional view of a moditied form of latching mechanism;

FIGURE 13 is an exploded view, partially in section, showing the modiiied form of latching mechanism in FIGURE 12;

FIGURE 14 is a transverse sectional view taken along line 14-14 in FIGURE 12;

FIGURE 15 is a transverse sectional view takenk along line 15-15 in FIGURE 12; and v FIGURE 16 is a transversesectional View taken along line 16-16 in FIGURE 12. Y

Referring speciiically to the drawings, the automatic .nailer is designated broadly by the reference numeral 10.

The automatic nailer 10 has a housing or casing 11 which ,may be described as being a hollow cylinder. The cylinder 11 has -a pressure chamber 12 provided in its upper interior portion for a purpose to be subsequently described. The Iupper end of the cylinder 11 is closed by a cap member 14 which is suitably secured to the upper end portion of lcylinder 11 by means suchas a threaded connection 15. j n w The cap Vrnernber 14 A' `cludes. a cylindrical collar 16 which extends above the upper end of cylinder 11 and 4 is provided with a centrally located bore 17 extending completely therethrough. The cap member 14 also is provided with a circular ange portion 20 which overlies the upper end of the cylinder 11 and a idownwardly extending tubular portion 21 which projects Within the upper portion of the cylinder 11 for a substantial distance.

Latchz'ng Mechanism Referring to FIGURES 8 and 9, there is shown an improved latching mechanism 22 which comprises a latch body 23 telescopically and slidably received within-the tubular extension 21 of the cap member 14. Thellatch body 23 is provided with a centrally locateddownwardly opening recess Z4 which is adapted to receive a control member or pin 25 secured to the upper end of a piston 26. A plurality of inclined bores 27 are formed in the latch body 23. Each ofthe bores 27 originates adjacentV the upper surface of thelatch body 23 and extends at an tangle of approximately 50 degrees with respect 'toY the axis of the latch body 23 inwardly into communication with the recess 24 formed therein. Partially protruding within the recess 24 are locking members shown as ball elements 30, four in number (see FIGURE 10), which are mounted within each of the bores 27. A coil spring Y 31 is also received in each bore 27 and is positionedin back of the bali element 30 therein. An annular groove 32 is formed in the upper portion of the latch body 23 about its exterior surface and extends across the opening to each of the bores 27. Within the groove 32, lhere is a spring ning 32a which lacts as a retaining means for -the coil springs 31.

The upper surface of the latch body 23 has a medially i positioned, upright cylindrical shaft 33 integral therewith and extending therefrom through the bore 17 formed -in the `cylindrical collar 16 of the 'cap member 14. The upper portion of shaft 33 extends beyond the vcap mem`- ber 14 and is threaded as at 34. A coil spring 35-eni i circles the upper portion of shaft 33 and is seated at one end against the cylindrical collar 16 of the cap member 14 and -at the other end against a retainer nut 36 threaded upon the upper portion off the shaft 33. A jarrnb nut 37 may be 'threaded upon the shaft 33 above the retainer nut 36 to prevent its from shifting position by becoming untihreaided or loosened on the shaft 33. The tubulary extension 21 on' the cap member 14 may include a plurality lof vents 38 which are positioned adjacent each of the inclinedbcres 27 formed in the latch body 23. The

shaft 33 is `sealed to the wall deningbore I17 in the cap v y member 14 by suitable means, such as an O-ring 40. A resilient bumper pad 41 made of a suitable material, such as neoprene, may be positioned between the upper surface of the latch body 23 andthe cap member 14 and is suitably .apertured to receive the shaft 33.

The Ilatch body 23 is provided with a bore 42 which conmmnicatesrwith the recess 24. The lower end of the latch body 23 is formed with arcounter bore 43, thereby defining a shoulder 44 between the bore 42 and the counter bore 43. An annular cam washer 4S of L-shaped cross-section isslidafbly received within the counter bore 43 land projects Within the bore 42.. The cam washer l.

45 includes a diskdike flange poi-tion 46 received by the counter bore 43 and an upright cylindrical leg 47 Which. projects within the bore 42. The upper end of the cylindrical leg 47 is beveled inwardly vto provide a cam surface48. The cam washer 45 is retained in position within the latch body V23 by suitable means, suchas a split ring retainer 50 secured in the wall defining the i '51, like the cam washer 45, includes a disk-like an`ge52 and an upright cylindrical leg "53 which is adapted to J abut the lower surface of the disk-like flange 46 of the cam washer 45. A shoulder 54 is formed in the tubular extension 21 against which the disk-like ange 52 of the stop washer 51 abuts. A suitable split ring retainer 55 is positioned immediately below the stop washer 51 in abutment with the disk-like flange 52 thereof and secured in the tubular extension 21 to maintain the stop washer 51 against axial movement relative to the tubular extension 21.

Referring to= the control member tor pin 2'5, its upper portion includes :a Icylindrical surface 56 immediately below which -is a .beveled cam surface 57 tapering inwardly, preferably at an angle of 52 degrees with respect to the axis of the control prin 25, which coincides with the axis of the latch body 23, thereby slightly exceeding the angle dened by each bore 27 with respect to the axis of the latch body 23 to insure latching between the ball elel ments 30 `and the control pin 25. The lower end of the control pin 25 is threaded `as at 60 and is received in the upper end of the piston 26 |by -a threaded bore 61 provided therein. Additional means may be provided to insure a 11i-gid connection between the control pin 25 and the piston 26, such Ias silver soldering between the threaded lower end 68 of the control pin 25 and the threaded bore 61. A jamb nut 62 may `be threaded about the control pin' 25 into `abutment with the upper end of the piston 26 to `further lock the control pin 25 in position. i

Nail Driving Assembly The piston 26 comprises a lower cylindrical portion 63 and an upper enlarged cylindrical collar 64 which is adapted to be slidably received in the cylinder 11. The cylindrical portion 63 and the collar 64 of the piston 26 dene a shoulder 65 therebetween. A centrally located bore 66 is formed in the lower end of the piston 26 vand houses a nail driving plunger 67. The nail driving plunger 67 includes an enlarged cylindrical mounting portionV 70 which is loosely received in the bore 66 and a lower rodlike portion 71. The relatively loose t between the piston 26 and the plunger 67 permits an easy substitution of the plunger 67 should it become worn or damaged after prolonged use. Since the junction between the enlarged mounting portion 70 and the rod-like portion 71 of the' plunger 67 is subjected to severe strain, it is flared as at 72 to lessen the possibility of metal fatigue at this point. At an intermediate point on the mounting portion 70, a transverse elongate bore 73 is provided therein. The transverse b ore 73 receives a pin connector 74 which extends through suitable apertures formed in the piston 26. It

will be noted that the bore 73 is of somewhat elongated depth but tof substantially equal width relative to the diameter of the pin connector 74 to prevent the transfer of the percussive force from the nail driving plunger 67 to the pin connector 74, thereby substantially eliminating the possibility of the pin connector 74 being sheared. The pin connector 74 serves -to hold the nail driving plunger 67 within the bore 66 formed in fthe piston 26 and to retract the plunger 67 when the piston 26 is retracted.

A connector element 75 is welded to the lower end of the cylinder 11 and includes an internal shoulder v76. A coil spring 77 encircles the lower cylindrical portion 63 of the piston 26 and the nail driving plunger 67, its opposite ends being seated against the shoulders 65 and 76, respectively. The enlarged collar portion 64 of the piston 26 may be `provided with a groove seating a suitable packing, 'such as an O-ring V80, to form a seal between the piston 26 and the cylinder 11, thereby preventing leakage of pressure lluid from the chamber 12 past the piston 26. It should be noted .that a slight clearance is formed between the cylinder 11 and the enlarged collar portion 64 of the piston 26 by the O-ring 80 interposed therebetween. This arrangement substantially prevents the scoring of the cylinder wall due to the introduction of foreign matter be-- tween the cylinder 11 and the piston 26. Suitable vent holes -81 may be provided in the lower portion of the cylinder 11 to prevent the accumulation of back-up pressure within the cylinder 11, and suitable brackets 82 may be welded .to the cylinder 11 to serve asa means for attaching the nailer 10 toa support.

Nail Holding Receptacle A nail holding receptacle or nose-piece 83 is suitably secured to the lower end of the connector element 75, as by a threaded connection 84. The upper end of the nail holding receptacle 83 extends flush with the shoulder 76 formed within connector element 75. A tubular resilient cushioning element 85 is positioned upon the upper end of the nail holding receptacle 83 rto loosely receive the rod-like portion 71 of the nail .driving plunger 67 and extends within the cylinder 11. The cushioning element 85 may be made from any suitable yresilient material, such as neoprene, and has upper and lower chamfered ends 86.

The nail holding receptacle 83 Iis preferably of the typer disclosed and claimed in copending United States applica-l alinement with the axis of the rod 71 of the nail driving plunger 67. The bore 88 is adapted lto slidably and telescopically receive the rod portion 71 of the nail driving plunger 67 which is therefore in position to drive a nail N held within Ythe bore 88 into the desired position. Means are provided for insuring that the Vnail N assumes a proper alined position within the bore 88. The nail positioning means includes an inwardly and upwardly inclined bore 90 formed in the removable plate 37 in the upper portion thereof and communicating with the centrally located bore S8 in the receptacle 83. A ball element 91 is. accommodated within the inclined bore 90 andv partially protrudes into the bore 88. A coil spring 92 is received within the inclined bore 90 in back of .the ball element 91 and serves as a resilient back-up means therefor. An abutment plate 93 covers lthe exterior opening of the inclined bore 90 to seat one end o-f the coil spring 92. The iabutment` plate 93 may be suitably secured to the removable plate 87 by means such as a screw S (see FIGURE V11). In the lower portion of the removable plate 87, there is a similar assembly comprising an inwardly and upwardly' ftioned in the inclined bore 94 behindthe ball element 95.

An abutment plate 97 covers the exterior opening of the inclined bore 94 to seat one end of the coil spring 96 and is suitably secured to Ithe removable plate 87 by means such as a screw `(in a manner similar to that shown in FIGURE 11). Immediately above the upper one of the inclined bores 90, 94 and within the centrally located bore 88, there is formed .a recess 100 of arcuate cross-section.

Between the upper and lower inclined bores 90, 94 `formed'in the removable plate 87 of the nail driving receptacle S3, there is provided an intermediate transverse bore 101 located immediately above the lower inclined bore 94 and communicating with the centrally located I intermediate bore 101. r On the side of the receptacle 83 remote fromthe removable plateV 87, an elongate slot 107 is formed` TheV elongate slot 107 extends for a distance somewhat greater than the length of the nails N which are to be used with the nailerl and communicates with the bore 88. The slot 107 is defined by upper and lower inwardly and downwardly inclined-surfaces l10S. Theupper inclined surface 108 is located opposite to the recess 100 and faces away therefrom. When a nail N -falls into place within the receptacle 83, the recess 100 is adapted to receive its head. The recess 100 tends to break the momentum of Ythe nail N, thereby preventing it from bouncing away from the wall defining bore 88 a distance great enough to permit it to assume a cocked position within the nail holding receptacle 83, while nevertheless allowing it to swing about its head through the elongate slot 107 to dissipate its momentum. v

Nail Feeding Assembly The track land feeding mechanism for delivering nails rto the nail holding receptacle 83 will nowbe described. Referring to FIGURES 8 and l1, there'is shown a track '109 Ifor feeding the nails into the bore 88 of the nail holding receptacle 83. The track 109 is suitably secured adjacent the Vside of the receptacle 83y containing the elongate slot 107. The track 109 extends upwardly from the nail holding receptacle'83 in inclined relationship with respect thereto,-whereby the nails N may he fed downwardly through the action of gravity. The track 109 includes a at Itop portion 110 (see FIGURE 5) from opposite sides of which depend downwardly extending spaced guideways 111. Each of the guideways 111 includes an inwardly extending ledge or shoulder 112 upon which .the head of a nail N is adapted to ride.

Spaced a suitable distance away from the nail receiving receptacle 83 and positioned astride the track 109 is a gate mechanism 113 for individually releasing nails Vdown the track 109. Referring to FIGURE 5, the gate ,mechanism 113 includes a housing 114 having a top wall 115, a bottoni wall 116, and side walls 117, 118 (see FIGURE 8). The top' wall 115 includes an intermediate portion 121 which projects inwardly (see FIGURE 8) thereby providing oppositely disposed recesses which accommodate the side walls 117 and 118, respectively. The bottom wall 116 is received between the side walls 117, v118 in Hush relationship with their lower edges. Refer- 'ring to FIGURE 5 once again, the forward end of the housing 114- is closed by an `end wall 122 suitably secured tothe top and bottom walls 115, 116 by means, such as lscrews T. The housing 114 therefore defines an open end chamber 123 which slidably accommodates a plunger assembly 124. The plunger assembly 124 includes a curved pressure -plate 12S positioned outwardly .of the housing 114 and suitably secured to a plunger element 126 by means, such as a screw U. The plunger 126 is provided with an intermediate transverse slot 127. `Positioned forwardly of the slot -127 and carried by plunger 126 is a gate 130. I111e gate 130` includes a downwardly extending base 131 suitably secured to the plunger 126 at the lower end of which is a transverse arm 132 extending at approximately a right angle therefrom. It will be noted in FIGURES 6 and 11 that the transverse arm 132 is cylindrical `for approximately half of its length with the outermost portion being tapered as at 133. Positioned rearwardly of the slot 127 is a second gate member 134 slightly odset from the gate member 130 and which includes a downwardly extending base 135 suitably secured .to the plunger 126 and a transverse tapered arm 136 extending at right angles from the base 135. In FIGURES A6 and l1, the arm 136 is shown as being tapered throughout substantially its entire length. The transverse arms 132, 136 of gate members 130, 134 are at all times in spaced, partially overlapping, generally parallel-relationship wit-h respect to each other. (See FIGURES 5, 6 land l-l.) The bottom wall 116 of the housing 114 is suitably slotted as at 14d and 141 to accommodate the 8 bases 131, 135 of the gate members 130, 134. The guideways 111 of the track 109 include transverse slots 142 and 143 positioned immediately below the inwardly extending shoulders or ledges 112 formed thereonk to accommodate the transverse arms 132, 136 of the gate members 130, 134. Between the forward end of plunger 126 and the end wall'122 of the housing 114, there is positioned a coil spring 144. The end wall 122 is preferably provided with a recess 145 to seat the coil spring 144; i

It will be noted in FIGURES 5 and 8 .that a threaded stud element 146 extends through the top wall 115, the

slot 127 formed in the plunger 126, the bottom wall 116,

and the top 110 of track `109. The threaded stud element 146 acts as a limiting stop means for the plunger 126 as Y it is adapted to abut one of the opposite end walls defining the slot 127 formed in the plunger 126 during movement of the plunger 126 within the housing 114 in either direction, as shown by the arrows in FIGURE 5. As shown in FIGURE 8, L-shaped brackets 147 may be provided adjacent the side walls v117, 118 of ythe housing 114 of gate mechanism 113 to secure it in place on the track 109.y

Positioned adjacent the nail holding receptacle 83 but spaced from the gate mechanism 113, there is a slowdown attachment 150 secured to the lower portions ofV the `guideways 111 by suitable means. The slow-down attachment 150 lcomprises a pair of oppositely disposed .Y Y

L-shaped members `151, 152, the lowermost legs of the I -shaped members 151, 152 extending beneath the lowerl y edges of the corresponding guideway 111 and includ-ing complementary scalloped edges which form a sinusoidal path 153. n t

n Operating M echunsm the three-way valve 16%) to a source of compressed air operated in place of the solenoid 173.

or other fluid pressure.

around the circumference of the tubular housing 163. Y

Rotatably mounted within .the tubular valve housing 163 is a valve cylinder 165 having oppositely disposed-V curved passageways 166 and 167 formedptherein; 'Attached to one end of the rotatable valve cylinder 165 is a lever,` arm 170. A-coil spring 171 is suitably secured to thel end of the lever arm .170 remote `from the val-ve cylinderV 165 and is anchored to the track 109 by Suitable means, such as a bar 172.' A solenoid, diagrammatically illustrated at 173, may he provided to actuate the levery 170 from closed'position (as shown in full lines in FIG- URE 1) (to open position (as shown in phantom lines in FIGURE l). It will be understood that 4t-he actuating means 1541er the. automatic nailer 10 as shown in FIG- URES l to 4, inclusive of the drawings is merelyillustrative and it is contemplated that any other suitable actuating .means 154 operating on the same principle may be used with the automatic nailer 10 within the spirit of this invention. For example,`-the Ithree-way valve 160 and the solenoid 173 could be mounted directly on the' nailer casing 11, orthe nailer 10 could tbe provided with a mechanical trigger mechanism which is manually In addition, if desired, solenoid means may be used to actuate the gate mechanism 113'for 4feeding nailsin'placc of the valve l arrangementshown. s

A third conduit '162 extends from the three-way valve 160 into close proximity with j Sequence of Operation The operation `of the automatic nailer will now be described. Prior to the power stroke or nail-driving stroke of the piston 26 'and its attached nail-.driving plunger 67, the piston 26 is secured in latched position within the cylinder 11 by the latching mechanism 22. When rthe piston 26 is secured in this position, the lower end of lthe rod-like element 71 of the nail-driving plunger 67 normally protrudes slightly within the bore 88 formed in lthe nail holding receptacle 83, as shown in FIGURE 8. A nail .N is alined within the bore 88 so that its longitudinal axis is substantially alined with that of the bore 88. This precise alinement of the nail N is accomplished bythe upper and lower ball elements 91, 95 which extend partially within the bore 88. The upper ball element 91 provides an abutment for the head of the nail N which rests thereupon and the lower ball element 95 assures that the shank portion of the nail N is spaced outwardly rfrom the wall defining the bore 88. It will be observed in FIGURE 8 that the tip of the nail N is unsupported and does not protrude from the lower end of 4the receptacle 83. The magnet i105 is effective to attract the shank of the nail N .toward it, thereby assuring that the nail N will assume a position which is substantially centered within the bore 88 for-med in the nail holding receptacle S3. This type of assembly creates little possibility for .the nail .N .to become cocked in the nail receiving receptacle S3 with a resulting mistire of the nail-driving plunger 67 which may either decapitate the nail N on its power stroke .or crumple the nail N into a somewhat useless pretzel.

Prior to the admission of fluid pressure into the chamber 12 formed linthe cylinder 11 between the latching mechanism 22 and the upper end of the piston 26, the control pin 25 rigidly secured to the top of the piston 26 is held in releasable latched engagement by the ball elements 3). The beveled -surface 57 on the control pin 25 is engaged by the ball elements 30 which protrude beneath this surface, thereby retaining the control pin 25 and consequently the piston 26 rigidly secured thereto in a retracted latched position. When less than a predetermined amount of pressure is present in the chamber 12 between the latching mechanism 22 vland the piston 26, the latch body 23, the ball elements 30 and the annular cam washer 45 carried by the latch body 23 are biased upwardly by the coil spring which encircles the shaft 33 of the l-atching mechanism 22. The upward movernent of the latch body 23 relative to the .tubular extension 21 of the cap member 14 is limited by the engagement `of the bumper pad 41 between the cap member 14 and .the upper surface of .the latch body 23. At this time, the annular cam washer 45 rests against the split ring retainer Sii and the cam surface 48 on its upright cylindrical flange 47 serves as a means -to retain the ball elements Sti partially within their respective inclined bores 27.

Referring to FIGURE l, when the operator actuates the solenoid 173 by manually depressing a push-button switch .to complete an electrical circuit therethrough, the lever arm 17@ is moved to the position shown in dotted lines, `thereby rotating the valve cylinder 165 until it assumes the position shown in FIGURE 4. A suitable source of pressure fluid, such as compressed air, is immediately delivered through conduit 161 and the valve passageway 167 to conduits 157 and 155 which communicate with the pressure chamber 12 in the cylinder 11.

The pressure of the compressed air introduced intothe chamber 12 must :have a predetermined value which is suiciently great to overcome the action of the coil spring 35 in biasing the latch body 23 upwardly. When the amount of pressure in the chamber 12 is great enough to overcome the action of the coil spring 35, the latch body 23 and the elements carried thereby are moved downwardly with respect to the cylinder 11 and the tubular portion 2'1 ofthe cap member 14. It will be apparent that such downward movement of the latch body 23 and the elements carried thereby is brought about by the incidence of the pressure in chamber 12 against the upper end of piston 26 which forces the piston 26 ldownwardly for a limited distance. During this stage, the piston 26 is held in latched engagement with the latch body 23 by the coaction between the control pin 25 and the ball elements 30 so that the limited downward movement of the piston 26 is effective to 'draw the latch body 23` downwardly. The cam washer 45, upon an incremental downward movement of the latch body 23, is engaged by the cylindrical leg 53 of the stationary stop washer 51 carried by the tubular extension 21 of cap member :14. 'Iihe continued downward movement of the latch body 23 results in the cam washer 45 being shifted upwardly relative to the latch body 23 by virtue lof its abutment with the cylindrical leg 53 of the stop washer 51. It follows that the beveled surface 48 on the upright -cylindrical leg 47 of the cam washer 45 cams each of the ball elements 30 outwardly and upwardly in their respective inclined bores 27 against the coil springs V31. 'llhe position of the ball elements 30 and the control pin 25 is so designed that a minute movement of the ball elements 30 within' their respective bores 27 is sufficient to disengage them from the beveled cam surface 57 of the control pin 25 to rele-ase it. The cam washer 45 is limited therefore in its upward movement relative to the latch body 23 by the shoulder 44 against which the disk-like flange46 of the cam washer 45 is adapted to abut. space Ibetween the lower end of the latch body 23 and the disk-like flange 52 of -stop washer 51, when the control pin 25 is in latohed position, must be sufficiently great to permit the latch body 23 t-o move downwardly enough to eiect the release of the control pin 25.

The `disengagement of the ball elements 30 with the beveled cam surface 57 of the control pin 25 takes place instantaneously thereby permitting the piston 26ste begin its power stroke smoothly and without interruption. Upon the release of thecontrol pin 25, the ball elements 3Q are returned to their original positions, partially protruding from their respective inclined bores 27 within the recess 24 of the latch body 23, by the coil springs 31 in wlhich positions they rare retained by the cam surface 48 on the cam washer 45. Y

The piston 26 travels rapidly downward in the cylinder 11 carrying the -nail dri-ving plunger 67 therewith. The rod-like member 71 of the nail driving plunger 67 penetrates deeply within the bore `88 of the nail holding receptacle 83 to strike the bead ofthe nail N held in position therein with terrific force thereby driving it into position wit-h a single power stroke of the piston 26'. The shock of the downward movement of the piston 26 is partially absorbed. by the resilient cushioning element 85. The charnfered ends 86 of the resilient cushioning element 85 allow 'for greater flow of the resilient material of the cusi ioning element when it is placed under compression vby y the downwardl movement of the piston` 26. When-the downward power stroke of the piston 26 has been completed, the individual coils lof spring 77 are compressed together and exert a strong upward torce against the piston 26. l

'Iihe actuation of the solenoid I173, the subsequent release of the piston 26 trom the lat-ching mechanism 22, and the downward power stroke of the piston 26 which follows occur almost instantaneously. Upon release of the push-button switch by the operator, the electrical circuit through the solenoid 173 is broken which de-energizes the solenoid 173. At the completion of this stage in the `sequence of the operation of the nailer 10, the solenoid 173 has become de-energized, thus allowing the coil vspring 171, which has been placed under tension by the.

prior actu-ation ofthe solenoid i173, to return to its original unstretched condition. The lever arm -170 attached to the coil spring 171 is accordingly moved to the position shown It will be understood that the Y 1 1 in lfull lines in FIGURE 1. This movement of the lever arm 171) rotates the valve cylinder 165 whereupon it assumes the position shown in FIGURE 3. When the valve 160 is in this position, the conduit 157 is connected to .the

i -conduit 162 through the curved passageway 166 in the valve-cylinder 165, providing an exhaust passageway for the compressed air trapped above the piston 26 in the cylinder 11. When the compressed air above the piston 26 has been suiiciently exhausted from the cylinder -11 through this passageway, the tightly compressed coils of spring 77 expand to move the piston 26 upwardly in the cylinder 11, whereby the control pin 25 enters into the recess 24 formed in the latch body 23 and is again lato'hed in place by the action of the ball elements 30 camming against the beveled surface 57 on Ythe control pin 25.

It is thus apparent that the compressed air in the chamber 12 above the piston 26 is exhausted from the cylinder 11 through the same conduits 1'55, 157 which delivered the compressed air to the chamber 12, before passing to the valve 160. The movement of the piston 26 as it is being retracted upwardly by the coil spring '77 aids in exhausting the remaining vestiges of compressed air from the chamber 12. The vent holes `81 which are provided in the lower portion of the cylinder 11 prevent the build up of back-up pressure occasioned -by the constant reciprocation of the piston 26.

As previously noted, when the valve 160' is in the position shown in FIGURE 3, the conduit 157 is connected lto the conduit 162 through the curved passageway 166 in the valve cylinder 165. Therefore, the exhausted compressed air is led through conduit 162 into proximity with the curved pressure plate 125 of the gate mechanism 113 as shown in FIGURE 5.

It will thus be observed that the exhaust pressure emanating from conduit 162 impinges upon the curved pressure plate 125 to urge the plunger 126` against the action of the coil spring i144. This movement of the plunger 126 and the gate members 138, 134 carried thereby Idetaches the lead nail N from the remaining nails by sandwiching it between the transverse arms 132, 136 of the gate members 130, 134. The continued movement of the plunger 126 and the gate members 130, 134 against the action of the coil spring 144 releases the lead nail N for its descent down the track 109 while maintaining the remaining nails in place. When the exhaust pressure has spent itself against the curved pressure plate 125, the coil spring 144 which has been compressed by the movement of the plunger 126 expands to its normal length thereby retracting the plunger |126 and the gate members 13), 134 carried thereby to their normal position within the housing 114. The retracting movement of the gate members 130, 134 allows the succeeding lead nail to assume a proper position for release upon a subsequent activation of the gate members 130, 13d.v The head of the nail N is supported by the ledges 112 formed on the opposite guide-ways 111 of the track 109 yas it descends down the track 189. The incline of the track 109 is suiciently great to permit each nail to fall from a stationary positionl thereon under the action of gravity without'any other propulsion means.

During its descent down the track 109, the nail N Vaccelerates rapidly which could cause it to bounce with considerable Iforce against a wall defining the bore 88 in the nail holding receptacle 83. Allowing the nail N to yfall freely under the influence of gravity into the nail holding receptacle 83 frequently results in the shank of the nail'being dipped outwardly beyond the elongate slot 107 formed in the nail holding receptacle 83. After which, the nail slips downwardly past the upper ball element 91 and is unable to return to an alined position in -the bore 88 causing `the nail to become badly cocked in the nail holding receptacle 83 and preventing proper driving of the nail. To overcome this problem in feeding nails by gravity, the slow-down guideway 150 is attachedto the track 109 adjacent the lower end thereof.

12 The shank of the nail N must follow the sinusoidal path v153 formed by the slow-down guideway150 which results in decelerating the nail N as it approaches the receptacle 83. The nail N continues its downward movement whereupon the head thereof strikes the arcuateshaped recess formed in the removable plate 87 in the nail holding receptacle l83 and momentarily catches thereupon. As this occurs, in most instances, the shank of the nail tends to bounce against the lower ball element 95 or the wall of the bore 88 and then rebounds outwardly through the elongate slot 107 eut in the opposite Aside of the nail holding receptacle 83 after which it begins its return to the bore 88. The head of the nail N is then engaged by the upper ball element 91 and the shank of the nail is maintained in proper alinement within the bore 88 by the lower ball element 95 and the magnet which attracts the same against the lower ball element 95. Thenailer 10 is then ready for the next cycle of operation.

A modified form of latching mechanism is disclosed in l FIGURES 12 to `16, inclusive, which operatesin asimilar manner to the latching mechanism 22 disclosed and described with reference to FIGURES 8 and 9 of the drawings. In FIGURES 12 to 16,' inclusive, similar reference numerals have been employed to designate elementsk which are common to those disclosed in FIGURES 8 and 9. Referring to FIGURE l2, it will be noted that-the lower end of the tubular extension 21 of the cap member 14 has a ygenerally conica-l interior surface 180. The

latch body 181 takes the form of a segmental tubular body. As shown, the latch body 181 has six identical segments 182, although it is contemplated that a greater' or lesser number of segments may be employed. On the upper end Yof `each latch body segment 182, there is Y formed a curved hook portion 183 which denes lan arcuate recess 184 of annular form in the latch body 181.

`At the lower end of each segment.\182, a shoe 185 is provided.k The shoe 185 comprises an outwardlytapering extension 186 having anouter conical surface adapted to cam against the conical surface 180k on the tubular extension 21 thereof of the cap member 14 and an in- 4wardly extending lug member 187. vThe shaft 33 extends through the bore 17 formed in the cap member 14 in a like manner to that disclosed in FIGURES 8 and 9 and includes the encircling coil spring 3S and its associated elements (not shown in FIGURE l2). The shaft 33 is provided with a collar 190 positioned withinV the cylinder 11 and spaced somewhat from the cap member "14 by thek resilient bumper pad 41 which is suitably apertured to receive the shaft 33.l The upper surface of collar 190 is formed with an annular recess 191 adapted -to receive the curved hook portion 183 of the segmental latch body 181. Below the recess 1911 formed in the collar 196, the collar has an arcuate edge 192 which isre'- `ceivedwithin the arcuate recess 184 formedin the segmental latch body 181. This arrangement permits' a limited pivoting action of the segmental latch body 181 about the Iarcuate edge 192 of the collar 190 for a pu-rf' formed between the individual segments 195 of .the holder" ring 194 are in radial alinement with the jointsform'ed between the individual segments 182 of the latch body 181. However, this alined relationship of these joints is not necessary. Adjacent the upper end of the holderring 194, there is an annular rib 196 projecting laterally outwardly therefrom. Therib 196 is adapted to engage the inner surfaces of the segments `182 of the latch body 181 to properly center the segmental holder ring 194 within the segmental latch body 181.

The segmental holder ring 194 at its lower end has a downwardly and inwardly depending foot 197 adapted to be engaged in mating relationship with the shoe 185 of the segmental latch body "181 and the control pin 25ct the piston 26. It will be noted that the foot 197 has a generally conical interior cam surface 200. The upper end of holder ring 194 has an annular groove 2111 formed therein to receive one end .of a coil spring 282. The coil spring 202 encircles the downward extension 193 on the shaft 33 and is seated at its opposite en'dagainst the lower surface of the collar 190. The coil spring 282 resiliently urges the holder ring 194 downwardly into abutting relationship with the inwardly extending lug 187 formed on the latch body 181. It will be observed that the lug has a recess 188 formed on its upper surface of generally triangular cross-section to matingly receive a projection 189 having a similar triangular cross-section formed on the segmental holder ring 194. The control pin 25 includes in its upper portion a cylindrical surface 293, immediately below which is an inwardly beveled cam surface 204 adapted to be engaged by the conical cam surface 280 formed on the interior of the foot 197.

When less than a predetermined amount of pressure is present in the chamber 12 between the latching mechanism 22 and the piston 26, the holder ring 194 grips the control pin 25 in the manner shown in FIGURE 12 to prevent downward movement of the piston 26. When sufficient pressure has been introduced into the chamber 12, the latching mechanism 22 moves downwardly against the upward biasing action of the spring 35 (not shown), such downward movement being brought about by the incidence of the pressure in chamber 12 against the upper end of piston 26 which forces the piston 26 downwardly. During this initial incremental downward movement of the piston 26, it is still held in latched engagement with the latching mechanism 22 by the coaction between the control pin 25, the holder ring 194 and the latch body -181 so that the downward movement of the piston 26 is effective to draw the entire latching mechanism 22 downwardly, whereupon the shoe 185 of the latch body 181 trave-ls downwardly and outwardly along the conical surface `181? of the tubular extension 2,1 causing the latch body l181 to` pivot outwardly to a limited extent about the arcuate edge 192 formed on the collar 190. The holder ring 194 is carried by the segmental latch body 181 during its outward pivoting movement. Accordingly, the segments V195 of the holder ring 194 are permitted .to spread apart sufficiently to disengage themselves from the beveled cam surface 204 formed on the control pin 25, thereby releasing the control pin 25 and the piston 26 rigidly secured thereto for the power stroke of the piston 26. The mating engagement of the projection 189 within the recess 188 insures the movement of the segmental holder ring 194 with the latch body I181 during the release of the piston 26, but not upon its retraction as will subsequently appear.

Whenthe pressure in the chamber 12 between the latch mechanism 22 and the piston 26 has been expended suiiiciently, the coil spring 35 draws the segmental latch body 181 upwardly, which results in the shoe 18'5 of the latch body 181 being moved upwardly and inwardly along the conical surface 18% of the tubular extension 21. This Ymovement of the shoe 185 causesthe latch body 181 to pivot inwardly about the arcuate edge 192 formed on the collar 190, thereby bringing the individual segments 195 l `to strike against theY lower end of the segmental holder ring 194. Thecontinued upward movement of the control pin 25 carries the segmental holder ring 194 upwardly also against the action of the coil spring 202.

As the segmental holder ring 194 travels upwardly along the inwardly extending lug member =187 of the segmental latch body 181, the individual segments 195 thereof pivot outwardly to a limited extent about their nib portions which form the rib 196. The extent to which the segments may pivot outwardly is limited by the abutment of their projection portions of the projection 189 with the' interior surface of the segmental latch body 181, but is suliicient to permit the lower portion of the segmental holder ring 194 to be spread apart for reception of the control pin 25 within the segmental holder ring 194.

Once the control pin 25 has penetrated the holder ring 194, `it no longer exerts any force thereon tending to urge the holder ring 194 upwardly, whereupon thecoil spring 202 resiliently presses the segmental holder ring 194 downwardly and assures that it will seat itself on the lug 187 formed on the latch body v181. The portions forming the projection 189 on each segment 195 of the holder ring 194 then are matingly received within the recess 188 to aline each segment 195 with respect to the latch body 181, whereby the holder ring 194 assumes its latching position.

The control pin 25 meanwhile may continue its upward movement until it strikes the rabutment extension 193` of the shaft 33. When the momentum created by the upward movement `ot the piston 26v has been arrested, the piston 26 and its control pin 25 settle downwardly, whereupon the beveled cam surface 204 of the .control pin 25 is again `gripped by the cam surface 200y formed on the holder ring 194 in latching engagement. Vent openings 205 may be provided in the tubular extension 21 an-d the segment-al latch body 181 to prevent `any accu-mula- .tion ot back-up pressure in the latching mechanism. Al-

though the description of the operation of [the modiiied -la-tching mechanism shown in FIGURES l216, inclusive, is of necessity somewhat lengthy, :it will be understood that the release of the piston and its subsequent re-latching by this mechanism occupies an extremely short interval of time.

Itis contemplated that each of the latching mechanisms may be used with-devices other than nailing machines where it is desired to releasably latch :an element in place. lt is further `contemplated that the machinek disclosed herein could be used to drive fastening elements other than nails, such as rivets, etc. Without departing from the spirit of the invention.`

-In the drawings and specication there have been set forth preferred embodiments of the invention and, although speciiic terms are employed, they are used in a generic sense .only and not -for purposes ot limitation, the scope of the invention bein-g defined in the claims.

We claim: n

1. In a lluid pressure operated device, la cylinder having a reciprocable piston mounted therein tor movement from retracted to extended position, means normally maintaining said piston in retracted position, said means comprising a latch mechanism positioned in the upper portion of said cylinder and a zcontrol pin rigidly secured to the upper end of said piston, said control pin extending within said latch mechanism yand being provided with a cam` surface, said,- latch mechanism having a plurality of cam elements disposed around said control pin, resilient means biasing said latch mechanism 'upwardly to engage said cam elements with sai-d cam surface in holding relationship,

said cylinder being provided 'with a chamber between said piston and said latch mechanism, a` conduit lfrom said chamber to a source of iluid pressure, whereby upon Sullicient pressure being built up in said chamber, theupward biasing action of said resilient means is overcome Vresulting in a substantially instantaneous release of said cam l surface by said cam elements thereby freeing said piston for its downward stroke to extended position.

2. In .a lluid pressure operated device, a cylinder having a reciprocable piston mounted therein, for movement from retracted to extended position, a pin secured to the upper end of the piston and extending within the upper portion of said cylinder, a centrally apertured cap secured over the top of said cylinder and having a tubular extension projecting within the upper portion of said cylinder, a latch body slidably positioned within said tubular extension and having va shaft extending from the upper sunt-ace thereof :through the .aperture in said cap, cam elements carried by said latch body, said pin extending into said latch body and having a cam surface, said cam elements being disposed radially outwardly of and yaround said pin, means encircling the por-tion of the shaft protrudin-g above the cap )for resiliently biasing said latch body and the cam elements carried thereby upwardly to engage said cam elements with said cam surface on the pin to hold said piston in retracted position, said cylinder having a pres' sure chamber between said latch body and said piston, a conduit connecting said chamber to a source of pressure iluid, 'whereby upon suliicient pressure being built up in said chamber, the upward biasing action of said mean-s is overcome to effect a release of the cam surface on said pin by saidcam elements thereby freeing said piston vfor its downward stroke to extended position.

3. A uid pressure operable nailer comprising; a housing having a reciprocable plunger mounted therein, latch means normally maintaining said plunger in retracted position, a nail holding receptacle secured Ito the lower end yof said housing, a track for delivering nails to said nail holdin-g receptacle, gate means Afor passing nails one at a time along said trackway to said nail holding receptacle, means for alternately introducing iluid pressure into said housing to disengage said latch means in effecting a power stroke for said plunger and exhausting fluid pressure from said housing in effecting the return of said plunger to its re- -tracted position maintained by said latch means, and means to actuate said gate means by the uid pressure exhausted lfrom said housing as said plunger returns to its retracted position, whereby said plunger is adapted to drive a nail downwardly from said receptacle on its power stroke and said gate means is adapted to release a single nail along the track to said receptacle as the plunger is retracted.

4. A pneumatically operable nailer comprising; a cylinder having a reciprocating piston therein, said cylinder being provided with a pressure chamber above said piston, latch means normally maintaining said piston in a retracted position, a nail holding receptacle secured to the lower end of said cylinder, a .track for delivering nails to said nail holding receptacle, gate means for passing nails singly down said track 4into said nail holding receptacle, means for alternately introducing compressed air into said chamber to disengage said latch means Afrom said piston in effecting a downward stroke` therefor and exhausting compressed air from said chamber in edecting the return of said piston :to its retracted position maintained by said latch means, said piston being adapted to drive .a nail from said receptacle during its downward stroke, and means to actuate said gate mean-s by the compressed air exhausted from said chamber as said piston returns to its retracted position for releasing a single nail down the track to said nail holding receptacle upon the vretraction of said piston within the cylinder.

5. A pneumatically operable nailer comprising; a cylinder having a piston recipro'cably mounted therein, Vlatch means adjacent the upper end of said cylinder normally maintaining said piston in retracted position, a nose-piece secured to the lower end of said cylinder and being provided with a bore for receiving a nail, a track for delivering nails to the bore of -said nose-piece, gate means for `passing nails one at Aa time along said track into the bore ofV said nose-piece, means for Ialternately introducing compressed air into said cylinder to disengage said latch means in elfecting a power stroke for said piston yand exhausting compressed air from said cylinder in eliecting the return of said piston to its retracted position maintained 4by said latch means, and means to actuate said gate means by the compressed air exhausted from said cylinder as said piston returns to its retracted position, whereby said piston is adapted to drive a nail downwardly from the bore of said nose-piece on its power stroke and said gate means is adapted to release a single nail along the track to the Ibore of said nose-piece as the piston'is and gripping said control member, resilient means biasing said latch means upwardly to normally retain said piston in latched position, said pressure chamber communicating with a source of pressure iiuid, a nose-piece secured to the lower end of said cylinder and being provided with a lbore extending downwardly therethrough, said -bore being in axial alinement with said plunger to slidably receive the same, means for positioning a nail withinV said fbore, a track secured to said nose-piece and communicating with said bore, gate means secured `to said trackA for delivering nails one at a time along said track to said lbore; means to alternately deliver pressure fluid to said pressure chamber :to increase the pressure Itherein to a predetermined amount to overcome the biasing action ofsaid resilient means whereby .the latch means instantaneously releases ysaid control member and permits said piston to be freely forced downward-ly, the plunger attached to said piston being adapted to drive a lnail outwardly from said bore in its downward stroke therewith, and to exhaust the pressure lluid -from said chamber in effecting the return of said piston to its latched position; and means to .actu-ate said gate means by the pressure iiuid exhausted from said chamber as said piston returns to its latched position, whereby a nail is released along said track for delivery to said bore within the nose-piece for the next downward stroke of said piston.

'7. A fluid pressure operable device for driving nails comprising; a cylinder, a plunger mounted in said cylinder for reciprocable movement therein, 4a control member secured to the upper end of said plunger and extending municating with said bore, gate means secured to said track for delivering nails one at a time along said track to said bore; means vto alternately deliyer pressure fluid 4to said pressure chamber increasing the pressure therein to a predetermined amount thereby 'releasing' ,sa-id :latch means from saidcontrol menrberV andpermitting said plunger to be freely forced downwardly, the plunger being adapted to drive a nail outwardly ,from said bore in its downward stroke, and to exhaust the pressure iluid from said chamber in eleoting the return of said plunger to its latched position; and means to actuate said gate means` by .the pressure fluid exhausted from said chamber as said plunger returns to its latched position, whereby aA i nail is released along said trackifor delivery tosaidbore 17 within the nose piece prior to the next downward stroke of said plunger.

8. A nail driving machine comprising; a cylinder having -a nail driving means mounted for reciprocation therein, latch means disposed within said cylinder for normally retaining said nail driving means in retracted posltion, a nail holding receptacle mounted on the lower end of said cylinder, an inclined track connected to said receptacle for delivering nails by gravity to said receptacle, gate means for delivering nails singly down said track into said receptacle, said cylinder having a pressure chamber positioned between said nail driving means and said latch means, said latch means comprising a pivotally mounted segmental latch body, a segmental holding ring carried4 within said segmental latch body, the upper end of said nail driving means being received within said segmental holding ring in gripped engagement thereby; means to alternately deliver pressure fluid to said chamber whereby said segmental latch body may pivot outwardly to permit said segmental holding ring to spread apart thereby releasing said nail driving means for its downward stroke, said nail driving means being adapted to drive a nail from said receptacle on its downward stroke, and to exhaust the pressure fluid from said chamber in effecting the return of said nail driving means to its retracted position; and means to actuate said gate means by the pressure fluid exhausted from said chamber as said nail driving means returns to its retracted position, thereby releasing a single nail down the track into said nail holding receptacle subsequent to the downward stroke of said nail driving means.

9. In a pneumatic tool having a cylinder, a piston reciprocably mounted therein for driving a fastening element and a control pin secured lto the upper end of said piston; improved means for normally holding said piston in retracted position within said cylinder, said imroved means comprising; a cap element threadably secured to the upper portion of said cylinder to close the same, said cap element having a downwardly extending tubular portion projecting within the cylinder, said cap element being provided with a centrally located bore extending therethrough, a shaft extending through said bore, said shaft being provided with a collar located within said cylinder, said collar having a recess formed in its upper surface, a segmental latch body having a curved hook portion formed on its upper end which is pivotally received within the recess formed in said collar, said latch body having an annular shoe formed on its lower end, said annular shoe being provided with an outwardly and downwardly tapering extension, said extension being in eng-agement with the lower end of the tubular portion of said cap element, said shoe having an inwardly extending annular lug portion; a segmental holding ring mounted within said latch body, said holding ring having a cam surface engaged with said control pin to normally retain said piston in retracted position, said holding ring being carried by the lug portion on said latch body, whereby upon a predetermined amount of pressure fluid being admitted to the interior of said cylinder, said latch body is adapted to pivot outwardly about said collar to a limited extent permitting said segmental holding ring to be spread apart sutiiciently to release the control pin of said piston.

l0. A nail driving machine comprising; a housing having nail driving means mounted for reciprocation therein,

latch means disposed within said housing for normally retaining said nail driving means in retracted position, al

receptacle mounted on the lower end of said housing and provided with a bore for receiving a nail, an inclined track connected to said receptacle for feeding nails by gravity to the bore of said receptacle, gate means on said track for restricting the feeding of the nails to one at a time down said track into the bore of said receptacle, means to alternately deliver pressure fluid to said housing to release said latch means Ithereby effecting a power stroke for said nail driving means and to exhaust the pressure uid fro-rn said housing in eifecting the return of said nail driving means to its retracted position, and means to actuate said gate means by the pressure Huid exhausted from said housing as said nail driving means returns to its retracted position, whereby said nail driving means is adapted to drive a nail downwardly from said receptacle on its power stroke and said gate means is adapted to release a single nail down kthe track to the bore of said receptacle as the nail driving means is retract-ed.

11. A nail driving machine as detined in claim 10, wherein a slow-down attachment is secured to Ithe lower portion of said track adjacent to said receptacle, said slowdown attachment providing a sinusoidal pathway for the lower portion of said track to reduce the speed of each nail prior Ito its entry into thebore of said receptacle.

l2. In a fluid pressure `operated device as set forth in claim l, wherein said latch mechanism comprises a latch body having a downwardly opening recess formed therein, said recess receiving the control pin of said piston, said latch body being provided with a plurali-ty of downward-ly inclined radially inwardly extending bores communicating with said recesses, said plurality of cam elements comprising ball elements respectively mounted in each of said plurality-of bores, and resilient back-up means in each of said bores behind said ball elements maintaining said ball elements in engagement with said cam surface on said control pin to releasably retain said piston in retracted position. y

13, In a liuid pressure operated device as set forth in claim 12, wherein a cam washer is slidably carried within said latch body below said ball elements and adapted toabut said ball elements, abutment means carried by said cylinder to restrict the downward movement of said cam washer, and saidk `abutment means forcing said cam washer upwardly relative to said latch body to cam said ball elements radially outwardly in their respective bores for releasing said cam surface on said control pin from engagement with said ball elements to free said piston for l its downward stroke in response to the increase of fluid pressure in said chamber causing downward movement of said latch body relative to said cylinder.

'14. in a neleasable latching mechanism for retaining an element inV a watched position means defining an outwardly tapered cam surface, segmental pivotal means mounted within said last-mentioned means and having a `complementary cam surface, holding means mounted within said pivotal means and adapted to grip said element, said pivotal means being adapted to ride down said outwardly tapered earn surface and pivot outwardly whereby said holding means may spread apart sutiiciently to release the latched element.

15. In a latching mechanism -for retaining .an element in a latched position, means ydefining 1an outwardly :tapered camming surface, segmental pivotal means mounted within said last-mentioned moms and having a complementary camming surface, segmental holding means mounted within said pivotal means and carried by the same to grip Asai-d element, said pivotal means being adapted to -ride down said outward tapering camming surface and pivot outwardly whereby said segmental holding means may spread apart sutliciently to release the latched element.

16. A fastener fee-ding ydevice for a fluid pressure operable tool having a housing with a reciprocable driver carrying piston therein, means to alternately supply and exhaust pressure uid to actuate said piston in a driving and return stroke, and a fastener hol-ding receptacle on the lower end of the housing; said feeding device comprising a track for delivering dasteners to said receptacle, gate means for passing fasteners one at a time lalong said track for delivery to said receptacle, and means to lactuate said gate means by the exhaust pressure iluid of said piston, whereby said gate means is actuated to deliver a fastener during said return stroke lof the piston.

17. A nail feeding device for a fluid pressure operable nailer having a cylinder with a reciprocable driver carrying piston therein, means to alternately supply and exhaust pressure lluid to Vactuate said piston in a driving and return stroke, and a nose-piece having a bore for receiving a nail secured to the lower end fof the cylinder; said feeding device comprising a track for delivering nails to the bore of said nose-piece, gate means .for passing nails one iat 'a time along said track into the bore of said nosepiece, and means to .actuate said gate means by the exhaust pressure fluid of said piston, whereby said gate means is actuated to deliver a nail during said return stroke of the piston.

18. A nail feeding device for la fluid pressure operable nailer having a housing with a reciprocable driver carrying piston therein, means to alternately supply and exhaust pressure fluid to -actuate said piston in a driving and return stroke, and la nail holding receptacle secured to the lower end of the housing; said feeding device comprising an inclined track connected to said receptacle for delivering nails by gravity to said receptacle, gate means ifo-r passing nails one at a time down said track for delivery into said receptacle, and means to actuate said gate means by the exhaust pressure fluid of @said piston, whereby said gate means is actuated to deliver a nail during said return stroke of Athe piston.

19. A nail feeding device as defined in claim 18, wherein a slow-down attachment is secured to the lower portion of said track adjacent to said receptacle, said slowdown attachment providing a sinusoidal pathway for the lower portion of said track to reduce the speed of each nail prior to its entry into the 'bore of said receptacle.

20. A pressure openable tool comprising a cylinder having a reciprocable piston mounted therein for movement from retracted to extended position, latch means disposed within said cylinder for normally retaining said piston 1in retracted position, said cylinder being provided with a chamber between said piston and said latch means, said latch means comprising a segmental latch body, 'a segmental holding ring carried by said segmental latch body in telescoped relationship therewthin, means on the upper end of said piston received within said segmental holding ring in gripped engagement thereby, means defining a tixed cam surface in said cylinder disposed radially outwardly with respect to said latch body and said holding ring, said latch body having a cam surface complementary to said fixed cam surtaee and in engagement therewith, means in said cylinder mounting the segments of said latch body forl pivotal movement, means Ato*k admit tluid pressure into said chamber, said cam sunface on said latch body sliding along said fixed cam surface and the segments yof said latch body pivoting outwardly in response to the admission of lluid pressure into said chamber, and the segments of said holding ring being carried by corresponding segments of said latch body to expand said holding ring for releasing said piston.

21. In a pressure operable tool comprising a housing having a reciprocable piston means mounted therein for movement from retracted to extended position, a latching mechanism -for retaining said piston means in retracted position, said latching mechanism comprising means in said housing deiining a fixed outwardly and downwardly tapered camming surface, an axially movable .annular collar within said housing, said lannular collar being disposed radially inwardly of said oamming surface and axially spaced therefrom, a segmental latch body pivotally mounted at one end on said annular collar, said latch body having an annular shoe on :its opposite end provided with an outwardly and downwardly tapered extension in engagement with said camming surface, a segmental holding ring mounted within said latch body land carried thereby, said latch `body co-nstricting said holding ring into gripping engagement with said piston means lto normally Y Y retain said piston means in retracted position, means to admit liuid pressure in said housing between said latching mechanism and said piston means, said collar beingV pulled axially by said piston means and said extension slidingV along said fixed camrning surface to pivot said latch body radially outwardly about said annular collar in response to the admission of lluid pressure into said' housing, and the segments of said holding rin-g being carried by corresponding segments of Said latch body in its radially outward pivoting movement to expand said holding ring and release said piston means.

References Cited in the file of this patent UNITED STATES PATENTS 916,768 Olsen Mar. 30, 1909 1,502,505 Karsky July 22, 1924 2,241,184 Clark May 6, 1941 2,290,256 Souter July 21, 1942 2,445,674 Kendall July 20, 1948 2,540,604 Van Sittert Feb. 6, 1951 2,585,941 JuilS Feb. 19, 1952 2,707,277 Aldrich May 3, 1955 2,786,450 Jacobus Mar. 26, 1957 2,946,313 Powers July 26, 1960 

1. IN A FLUID PRESSURE OPERATED DEVICE, A CYLINDER HAVING A RECIPROCABLE PISTON MOUNTED THEREIN FOR MOVEMENT FROM RETRACTED TO EXTENDED POSITION, MEANS NORMALLY MAINTAINING SAID PISTON IN RETRACTED POSITION, SAID MEANS COMPRISING A LATCH MECHANISM POSITIONED IN THE UPPER PORTION OF SAID CYLINDER AND A CONTROL PIN RIGIDLY SECURED TO THE UPPER END OF SAID PISTON, SAID CONTROL PIN EXTENDING WITHIN SAID LATCH MECHANISM AND BEING PROVIDED WITH A CAM SURFACE, SAID LATCH MECHANISM HAVING A PLURALITY OF CAM ELEMENTS DISPOSED AROUND SAID CONTROL PIN, RESILIENT MEANS BIASING SAID LATCH MECHANISM UPWARDLY TO ENGAGE SAID CAM ELEMENTS WITH SAID CAM SURFACE IN HOLDING RELATIONSHIP, SAID CYLINDER BEING PROVIDED WITH A CHAMBER BETWEEN SAID PISTON AND SAID LATCH MECHANISM, A CONDUIT FROM SAID CHAMBER TO A SOURCE OF FLUID PRESSURE, WHEREBY UPON SUFFICIENT PRESSURE BEING BUILT UP IN SAID CHAMBER, THE UPWARD BIASING ACTION OF SAID RESILIENT MEANS IS OVERCOME RESULTING IN A SUBSTANTIALLY INSTANTANEOUS RELEASE OF SAID CAM SURFACE BY SAID CAM ELEMENTS THEREBY FREEING SAID PISTON FOR ITS DOWNWARD STROKE TO EXTENDED POSITION. 